1. Field of the Disclosure
The present disclosure relates to a coating composition having excellent visible light transmittance, durability, and photoluminescence characteristics, and a wavelength converting sheet prepared using the same.
2. Background of the Disclosure
Since polyorgano-silsesquioxane exhibits high transparency, thermal resistance, photodegradation resistance, gas barrier properties, and the like, polyorgano-silsesquioxane per se or a mixture thereof with another polymer material is used as an insulation film, a hard coating agent, a high-hardness film, a photomask, a sealant for a light emitting device, and the like. A ladder-like polyorgano-silsesquioxane has a general structure such as the following Formula 1, and is advantageous in that other characteristics may be imparted according to the type of R-functional group and end group:

In a wavelength converting sheet, a matrix material having high transmittance in the ultraviolet, visible, and infrared light regions is required for absorbing only a partial wavelength region from light to convert wavelength and allowing the other wavelength regions to have a high transmittance of 90% or more. In general, examples of a matrix material utilized for the use of wavelength conversion include epoxy (—C—O—C—)-based or silicone (—C—O—Si—C—)-based transparent resins, and other acryl-based, vinyl-based, and carbonate-based transparent polymers. In order to form a coating solution using these resins and polymers, they are mixed with a wavelength converting agent, and the mixture is diluted in a solvent and used.
A wavelength converting sheet may be used as use of converting a wavelength of a light source in a device such as lighting, a self-light emitting diode (LED), and a solar cell (European Patent No. EP 2 261 300 B1; the official gazette of Korean Patent No. 10-1068866B1). In this case, when a wavelength converting sheet is continuously exposed to a light source, and thus a polymer matrix having low heat resistance and low photodegradation resistance is used, deterioration or yellowing is exhibited, and when used for a long time, light converting performance of a wavelength converting agent therein deteriorates, thereby leading to a gradual decrease in the wavelength conversion efficiency.
Therefore, there is an urgent need in the art for a wavelength converting sheet and a preparation method thereof in order to solve the above-described disadvantages.
Throughout the present specification, various patents and publications are referenced and citations are provided in parentheses. The disclosure of these patents and publications in their entities are hereby incorporated by references into this application in order to more fully describe this invention and the state of the art to which this invention pertains.